JP4803137B2 - Automatic engine stop device - Google Patents

Description

  The present invention relates to an automatic engine stop device.

Conventionally, for the purpose of improving fuel economy and emission, when a predetermined automatic stop condition is satisfied, the engine is automatically stopped, and when a predetermined restart condition is satisfied during the automatic engine stop, A system that performs so-called idle stop that automatically starts the engine is known (see, for example, Patent Document 1). As a restart condition in such an idle stop system, a first restart condition related to a driver's intention to start and a second restart condition related to a request on the vehicle side are generally set. is there. That is, the first restart condition is to depress the accelerator pedal, etc., and the second restart condition is to detect a decrease in battery voltage or charge state, or to operate the air conditioner (engine driven compressor Operation) is required.

Here, in the idle stop system disclosed in the above-mentioned patent document, when the door on the driver's seat side is opened after the engine is automatically stopped, the driver is warned and the engine is restarted.
JP 2005-307991 A

  However, if the engine is restarted by opening the door while the engine is automatically stopped, the engine will start even though there is no intention to start, so the driver may feel anxiety or discomfort. is there. Therefore, it is desirable not to restart the engine when the engine is automatically stopped and the door is opened.

  On the other hand, even when the engine is automatically stopped and the door is opened, for example, when a restart condition related to the battery state is satisfied, the engine is operated from the viewpoint of stabilizing the power supply to the electric load. It is desirable to restart.

  Therefore, when the engine is automatically stopped and the door is opened, the driver's anxiety and the like are reduced, and the necessity of restarting the engine related to the requirements on the vehicle side is compared and weighed. It is required to restart properly.

  The present invention has been made in view of the above points, and an object of the present invention is to restart an engine in an automatic engine stop device, particularly when the engine is automatically stopped and the door is opened. Is to do it properly.

According to one aspect of the present invention, an engine automatic stop device determines whether or not a predetermined automatic stop condition is satisfied, and automatically stops the engine when the automatic stop condition is satisfied. Including a first restart condition related to the driver's intention to start after the automatic stop, a battery condition that the voltage of the battery or the state of charge of the battery has fallen below a threshold value, and a condition relating to an operation request of the air conditioner, Automatic stop start control means for determining whether or not a second restart condition related to a request on the vehicle side is satisfied and restarting the engine when the first restart condition or the second restart condition is satisfied A door opening detecting means for detecting that the door of the vehicle has been opened, and receiving the opening of the door by the detection of the door opening detecting means during the automatic stop of the engine. Warning means for giving a warning when the door stop detecting means detects that the door has been opened during automatic stop of the engine. of the threshold of the battery condition, together with the battery condition is reduced to the difficulty Kunar so established, by canceling conditions regarding operation demand of the air conditioning system, sometimes the said battery condition is formed upright While the engine is restarted, the restart of the engine is prohibited even when there is a request for operating the air conditioner.

  According to this configuration, the automatic stop / start control means automatically stops the engine when the automatic stop condition is satisfied, and restarts the engine when the restart condition is satisfied after the engine is automatically stopped.

Thus, when the engine is automatically stopped and the door is opened, a warning is given by warning means. This alerts the occupant, particularly the driver, that the engine is being automatically stopped. Further and being automatic stop of the engine, when the door is opened, in the second restart condition, for battery conditions, whereas by lowering the threshold, the condition is the difficulty bitterness satisfied, This is canceled for conditions related to the operation request of the air conditioner.

Thus, for example, a voltage or state of charge of the battery to some extent, in a degraded state, even if the if the state in which no door is opened engine is restarted, the restart condition is rather the difficulty met If the engine is not restarted by being changed and the restart of the engine is suppressed, the battery voltage or the charging state further decreases, and the restart condition after the change is satisfied, The engine is restarted. Further, when an operation request for the air conditioner is made, the engine does not restart because the restart condition is canceled.

  Therefore, restart of the engine with the door opened is avoided as much as possible, so that the driver's anxiety associated with the restart of the engine is reduced, while the battery state is related. When the need for engine restart is high, the engine is restarted. Therefore, the balance between the driver's anxiety and the need for engine restart is optimized, and the engine is restarted appropriately. Is called.

The automatic stop and start control means, during the automatic stop of the engine, when the door is opened is detected by said door opening detecting means, the pre-noted threshold, changing only the smaller amount set in advance It is good also as.

Battery condition Works threshold is, by being changed only to a small value amount set in advance, and being automatic stop of the engine, when the door is opened, the battery becomes Li conditions hardly satisfied, the engine Is restarted as much as possible. Therefore, as described above, the balance between the reduction of the driver's anxiety and the like and the necessity of the engine restart is optimized, and the engine is restarted appropriately.

The engine automatic stop device supplies power to a main battery and a starter motor for supplying electric power to an electric load mounted on the vehicle while the engine is automatically stopped. The battery further includes a sub battery to be started, and a battery state detecting unit that detects a voltage or a charging state of each of the main and sub batteries, and the automatic stop / start control unit includes the main battery detected by the battery state detecting unit. voltage or on the basis of the charge state, the second battery condition included in restart condition is determined whether or not satisfied, may be.

According to this configuration, the power to the electric load in accordance with the state of the main battery supply, for whether or not to restart the engine is determined, when is substantially reduced voltage or state of charge of the main battery Even if the door is opened, the engine is restarted. This stabilizes the power supply to the electric load.

  The electric load to which electric power is supplied from the main battery may include a hill holder mechanism that maintains brake hydraulic pressure while the vehicle is stopped.

  That is, by stably supplying power to the hill holder mechanism, the vehicle can be reliably prevented from sliding down due to a decrease in the function of the hill holder mechanism.

  As described above, according to the present invention, when the engine is automatically stopped and the door is opened, the condition related to the battery state is changed so that the condition is difficult to be satisfied. By canceling the conditions related to the operation request of the air conditioner, the engine restart is avoided as much as possible, while the engine is restarted when the necessity is high. The balance between the reduction of anxiety and the like and the necessity of engine restart is optimized, and the engine can be restarted appropriately.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

-Schematic configuration of idle stop system-
1 and 2 show an embodiment of an idle stop system including an engine automatic stop device according to this embodiment. The system E includes an engine 1 including a cylinder head 10 and a cylinder block 11 and an ECU 2 (engine controller) for controlling the engine 1. As shown in FIG. 2, the engine 1 is provided with four cylinders 12A to 12D. Inside each of the cylinders 12A to 12D, pistons connected to the crankshaft 3 as shown in FIG. Thus, a combustion chamber 14 is formed above the piston 13 in each of the cylinders 12A to 12D.

  Here, in general, in a multi-cylinder four-cycle engine, each cylinder performs a combustion cycle composed of intake, compression, expansion, and exhaust strokes with a predetermined phase difference. In the case of a cylinder engine, when referred to as the first cylinder 12A, the second cylinder 12B, the third cylinder 12C, and the fourth cylinder 12D from one end in the cylinder row direction, the first cylinder (# 1), the third cylinder (# 3), Combustion is performed with a phase difference of 180 degrees in crank angle in the order of the fourth cylinder (# 4) and the second cylinder (# 2). Thus, the output torque accompanying the drive of the engine 1 is transmitted to drive wheels (not shown) via a torque converter connected to the crankshaft 3 and an automatic transmission (AT) 52 (see FIG. 3). become.

  A spark plug 15 for igniting and burning the air-fuel mixture in the combustion chamber 14 is provided at the top of each combustion chamber 14 of each of the cylinders 12A to 12D. An electrode is disposed so as to face the combustion chamber 14. Further, a fuel injection valve 16 is disposed on the side of the combustion chamber 14 (right direction in FIG. 1) with the tip injection hole facing the combustion chamber 14. This fuel injection valve 16 incorporates a needle valve and a solenoid (not shown) and is driven to open for a time corresponding to the pulse width in response to the input of a pulse signal from the ECU 2 so that an amount of fuel corresponding to the driving time is supplied. The cylinders 12A to 12D are configured to inject directly. The fuel injection direction is adjusted so as to be directed to the vicinity of the electrode of the spark plug 15.

  Although not shown, fuel is supplied to the fuel injection valve 16 via a fuel supply passage or the like by a fuel pump, and the fuel supply pressure is in the middle of the compression stroke of each cylinder 12A to 12D. Thereafter, the pressure is set higher than the pressure in the combustion chamber 14 so that fuel can be injected into the high-pressure in-cylinder combustion chamber 14.

  An intake port 17 and an exhaust port 18 that open toward the combustion chamber 14 are provided in the upper part of the combustion chamber 14 of each of the cylinders 12A to 12D. An intake valve 19 and an exhaust valve are provided in these ports 17 and 18, respectively. 20 are arranged respectively. These intake valve 19 and exhaust valve 20 are driven by a valve operating mechanism including a camshaft (not shown), and as described above, each of the cylinders 12A to 12D performs a combustion cycle with a predetermined phase difference. The opening / closing timing of the intake / exhaust valves 19 and 20 for each cylinder is set.

  Further, an intake passage 21 and an exhaust passage 22 are provided so as to communicate with the intake port 17 and the exhaust port 18, respectively. As shown in FIG. An independent branch intake passage 21a is provided for each of the cylinders 12A to 12D, and the upstream end of each branch intake passage 21a communicates with the surge tank 21b. The intake passage 21 upstream of the surge tank 21b is a common intake passage 21c common to the cylinders 12A to 12D. The throttle valve 23 adjusts the cross-sectional area of the passage 21c by, for example, a butterfly valve to restrict the intake flow. And an actuator 24 for driving the same, and an air flow sensor 25 for detecting the intake air amount is provided upstream of the throttle valve 23.

  On the other hand, a catalyst 29 for purifying the exhaust is disposed downstream of the collection portion of the exhaust passage 22 where exhaust from the cylinders 12A to 12D collects. The catalyst 29 may be a so-called three-way catalyst, but is not limited thereto, and may be a so-called lean NOx catalyst, for example.

  Further, the engine 1 is provided with an alternator 28 that is drivingly connected to the crankshaft 3 by a belt or the like, and the electric power generated by the alternator 28 is stored in a battery 80 as shown in FIG. It has become.

  Further, the engine system E is provided with two crank angle sensors 30 and 31 for detecting the rotation angle of the crankshaft 3, and the engine rotation speed is mainly based on a signal from one crank angle sensor 30. The rotation direction and the rotation angle of the crankshaft 3 are detected from the crank angle signals output from the two crank angle sensors 30 and 31 with the phases shifted from each other. In addition, the engine system E includes a cam angle sensor 32 that detects a specific rotational position of the camshaft and outputs it as a cylinder identification signal, and an ignition switch 33 that performs an on / off operation for manually switching between operation and stop of the engine 1. (IG switch), a vehicle speed sensor 34 comprising an electromagnetic pickup for detecting the vehicle speed, a door open sensor 35 for detecting that each door (not shown) provided in the vehicle is opened, and a brake for detecting the brake fluid pressure A fluid pressure sensor 36, an air conditioner switch 37 for operating an air conditioner for air conditioning the vehicle interior, and the like are disposed. Reference numeral 56 denotes a warning device including a warning lamp and a warning buzzer in the meter for performing various warnings for the driver. The warning device 56 is operated by the ECU 2.

  The ECU 2 receives signals from the sensors and the switches 25, 30 to 37, outputs a signal for controlling the fuel injection amount and the injection timing to the fuel injection valve 16, and an ignition device for the ignition plug 15. 27 outputs a signal for controlling the ignition timing, and further outputs a signal for controlling the throttle opening to the actuator 24 of the throttle valve 23. As will be described in detail below, the ECU 2 stops the fuel supply to each cylinder 12A to 12D (fuel cut) and automatically stops the engine when a predetermined engine stop condition is satisfied during idling. Thereafter, the engine 1 is automatically restarted when a predetermined engine restart condition is satisfied by the driver's brake operation or the like.

  Here, the engine 1 according to the present embodiment is capable of starting the engine 1 by itself without borrowing the force of a starting motor 54 to be described later when the engine 1 is restarted. That is, first, the first combustion is performed in the cylinder 12 in which the piston 13 is stopped in the middle of the compression stroke, and the piston 13 is pushed down, so that the crankshaft 3 is slightly reversed, thereby being in the expansion stroke. The piston 13 of the cylinder 12 is raised and the air-fuel mixture in the cylinder 12 is compressed. Then, by igniting and burning the air-fuel mixture in the expansion stroke cylinder 12 that has been compressed in this manner and whose temperature and pressure have been increased, a torque in the forward rotation direction is applied to the crankshaft 3, and the engine 1 is The engine is started (so-called combustion start).

  In order to start the engine 1 by itself, the torque in the forward rotation direction is applied to the crankshaft 3 as much as possible by the combustion of the cylinder 12 in the expansion stroke at the time of stop. , Abbreviated as TDC), the cylinder 12 must overcome its compression reaction force (compression pressure) and exceed TDC. Therefore, in order to start the engine 1 reliably, it is necessary to ensure sufficient air for combustion in the stop-time expansion stroke cylinder 12.

  At the same time, in order to improve the startability of the engine, it is necessary to keep the stop position of the piston 13 of the cylinder 12 in the expansion stroke within a predetermined range suitable for restart.

  Therefore, the engine 1 adjusts the intake air amount into the compression stroke cylinder 12 and the expansion stroke cylinder 12 at the time of stop by adjusting the opening degree of the throttle valve 23 or adjusts the power generation amount of the alternator 28 at the time of the automatic stop. The external load of the engine 1 is adjusted by the above.

  However, even if such control at the time of automatic stop is performed, the stop position of the piston 13 of the cylinder 12 in the expansion stroke may not fall within a predetermined range due to various factors. It is desirable to start the engine 1 with the starter motor 54 without restarting the engine 1.

  The engine 1 is provided with a starter motor 54 when starting the engine 1 for the first time or when the engine 1 cannot be restarted due to the combustion start described above. The starter motor 54 includes a pinion gear that meshes with a ring gear 55 that is fixed to the crankshaft 3. The pinion gear can be reciprocated between a meshing position that meshes with the ring gear and a retracted position that is distant from the ring gear. ing. When the engine 1 is restarted by the starter motor 54, the crankshaft 3 is rotationally driven, that is, cranked by moving the pinion gear and meshing with the ring gear 55 and driving the starter motor 54 according to control by the ECU 2. Will do.

  FIG. 3 shows a configuration of a power supply system according to the idle stop system, and this system is a two-battery system including two batteries of a main battery 80a and a sub battery 80b.

  The main battery 80a is a battery having a relatively large capacity. The main battery 80a is always connected to the vehicle electrical load 82 and mainly supplies power to them. The vehicle electrical load 82 is roughly divided into a first load group 82a, a second load group 82b, and a third load group 82c.

  The first load group 82a is an electric load among the general electric loads in which it is not desirable for the battery voltage to temporarily decrease during cranking by the starter motor 54. Specific examples include an airbag control unit, an EHPAS (electrohydraulic power steering) control unit, a navigation system, audio, and various meters.

  The second load group 82b is a general electric load that does not cause much problem even when the battery voltage temporarily decreases during cranking by the starter motor 54. Specific examples include various lights and defoggers.

  The third load group 82c is an electric load peculiar to the vehicle, and specifically includes a hill holder mechanism that prevents the vehicle from sliding down while stopping on a slope, a motor of an electric power steering, and the like. The hill holder mechanism covers that the power brake does not operate during the automatic stop of the engine 1, and the electric power steering covers that the EHPAS does not operate during the automatic stop of the engine 1.

  The main battery 80a is also connected to the starting motor 54 via the power relay 85. The power relay 85 is turned on and off by the ECU 2. When the power relay 85 is off, power is not supplied from the main battery 80a to the starter motor 54, and when the power relay 85 is on, power can be supplied from the main battery 80a to the starter motor 54.

  Further, the main battery 80a is always connected to the alternator 28, whereby the electric power generated by the alternator 28 is stored in the main battery 80a.

  The sub-battery 80b is a battery having a relatively small capacity, and is a battery dedicated to driving the starter motor 54 here. The sub-battery 80b is always connected to the starter motor 54, and power can be supplied to the starter motor 54. The sub battery 80b is also connected to the alternator 28 (main battery 80a) via the charge relay 87. On / off of the charge relay 87 is controlled by the ECU 2. When the charge relay 87 is on, the electric power generated by the alternator 28 is also stored in the sub battery 80b.

The main battery 80a and the sub-battery 80b are respectively connected to the ECU 2, and the ECU 2 determines whether each battery 80a, to determine the 80b of the state. ECU2 also depending on its the state, or the control of the power generation amount by the alternator 28, or perform the restart of the engine 1 as described below.

As described above, when the engine 1 is started by operating the IG switch 33 or when the engine 1 cannot be restarted due to combustion start, the engine 1 is started by cranking by the start motor 54. At this time, basically, electric power is supplied from the sub-battery 80b to the starter motor 54, and the starter motor 54 is driven. Since the power consumption of the starter motor 54 at the time of cranking is relatively large, the battery voltage of the sub battery 80b is temporarily greatly reduced. However, the vehicle electrical load 82 is supplied with power from the main battery 80a and is not affected by the voltage drop of the sub battery 80b. This is particularly effective in preventing a voltage drop with respect to the first load group 82a and the third load group 82c, in which a decrease in battery voltage is not desirable. Incidentally, the state of the sub-battery 80b, when only the power from the sub-battery 80b is not able to start the engine 1, the power relay 85 is turned on, from both the sub-battery 80b and the main battery 80a, Electric power is supplied to the starter motor 54.

−Automatic engine stop / start control−
Next, the automatic stop and restart control of the engine 1 executed by the ECU 2 will be described.

  FIG. 4 shows a flowchart relating to restart control after the engine 1 is automatically stopped. In addition, what is necessary is just to employ | adopt well-known control suitably about the control which stops the engine 1 automatically, and the detailed description is abbreviate | omitted here.

  Here, as the automatic stop condition in the automatic stop control of the engine 1, for example, a condition that the vehicle speed is 0 km / h, the accelerator pedal is off, and the brake pedal is on may be employed. Then, as the automatic stop control of the engine 1, the engine 1 may be automatically stopped when all of the above conditions are satisfied. During the automatic stop, as described above, the compression stroke cylinder 12 and the expansion stroke cylinder 12 at the time of stop by adjusting the opening degree of the throttle valve 23 so that the position of the piston of the engine 1 is optimized for the combustion restart. The external load of the engine 1 is adjusted by adjusting the intake air amount to the inside and adjusting the power generation amount of the alternator 28.

On the other hand, as a condition for restarting the engine 1 in the flow of FIG. 4, there is a start request due to the brake pedal being returned (brake off) and the accelerator pedal being depressed (accelerator on). That is, the first restart condition related to the driver's intention to start is set. Separately from this, the battery state is a predetermined state (battery condition) that the actuation of the air conditioner has been requested by the operation of the air conditioner switch 37 (air-condition) that a second of but contained at least Restart conditions are set. The battery condition is that the battery voltage or SOC of the main battery 80a out of the two batteries 80 of the main battery 80a and the sub battery 80b is detected, and the detected battery voltage or SOC is a set threshold value. It is determined that the battery condition is satisfied when the value is less than.

  Next, the restart control of the engine 1 will be described with reference to the flowchart shown in FIG. First, in step S11, it is determined whether or not the engine is in an idle stop, that is, whether or not the engine 1 is in an automatic stop. If NO in the idle stop, step S11 is repeated while the engine is in an idle stop. If YES, the process proceeds to step S12.

  In step S12 during idling stop, based on the signal from the automatic transmission 52, it is determined whether or not the shift position is in the D (drive) range or M (manual) range. If YES in the D range or M range, the process proceeds to step S19. If NO in the D range and M range, the process proceeds to step S13.

  In step S13, it is determined whether or not the door has been opened based on the detection value of the door open sensor 35. If the door has been opened, the process proceeds to step S14, while the door is not opened. Sometimes, the process proceeds to step S19.

  In step S14, the warning device 56 is activated, and a warning buzzer is used to warn the driver that the vehicle is idling. Then, in step S15, the air conditioner condition in the second restart condition is canceled, and in the subsequent step S16, the battery condition in the second restart condition is changed. Specifically, the establishment threshold value related to the battery condition is changed in a direction in which the battery condition is hardly established. That is, the threshold value of the battery voltage or the battery charge state (SOC) is lowered by a preset amount.

  In step S17, it is determined whether the second restart condition is satisfied. At this time, the air conditioner condition is canceled and the battery condition is changed. When the second restart condition is not satisfied, step S17 is repeated, while when the second restart condition is satisfied, the process proceeds to step S18.

  In step S18, the engine 1 is restarted. Although a detailed description of the restart control of the engine 1 is omitted, in the restart control, the engine 1 is restarted by combustion start when possible in accordance with the piston position of the stopped engine 1, and combustion is performed. When starting is impossible, the engine 1 is restarted by cranking by the starting motor 54.

  On the other hand, in step S19, it is determined whether the second restart condition is satisfied. Here, the second restart condition includes the air conditioner condition because the door is not open, and the battery condition is not changed. When the second restart condition is not satisfied, the process proceeds to step S110. When the second restart condition is satisfied, the process proceeds to step S18, and the engine 1 is restarted in the same manner as described above. To do.

  On the other hand, in step S110, it is determined whether or not there is a start request (in other words, whether or not the first restart condition is satisfied). If NO, the process returns to step S12, while the start request is made. If yes, the process proceeds to step S18, and the engine 1 is restarted in the same manner as described above.

  As described above, in the idle stop system, when the engine 1 is automatically stopped and the door is opened, the air conditioner condition is canceled (step S15), and the battery condition threshold is set to the battery condition. Is changed to the side where it is difficult to be established (step S16). As a result, when the engine 1 is automatically stopped and the door is opened (step S17), the second restart condition is less likely to be established than when the door is closed (step S19). The restart of the engine 1 is suppressed. Therefore, the driver's anxiety and discomfort associated with restarting the engine 1 when the door is open are reduced.

Also, depending on the state of the main battery 80a supplies electric power to the vehicle electrical load 82 while the engine 1 is stopped, from the viewpoint to a stable supply of electric power to the electric load 82, the need to restart the engine 1 is particularly When it is high, the engine 1 is restarted even if the door is open. As a result, electric power is stably supplied to the vehicle electrical load 82. In particular, the vehicle electrical load 82 includes a first load group 82a and a hill holder mechanism (third load group 82c) in which it is not desirable for the battery voltage to temporarily decrease. By supplying it, for example, the vehicle is prevented from sliding down.

  In this way, the balance between the reduction of the driver's anxiety and the necessity of restarting the engine 1 is optimized, and the engine 1 can be restarted properly when the door is open.

  In the above-described embodiment, the engine 1 is configured to be able to start combustion. However, the present invention is not limited to this. For example, the engine 1 may be configured to be capable of starting only by the starting motor 54.

  As described above, the present invention optimizes the balance between the driver's anxiety and the need to restart the engine, and can properly restart the engine when the door is open. Since it can, it is useful as an automatic engine stop device.

1 is a schematic configuration diagram of an idle stop system according to an embodiment of the present invention. It is a schematic diagram which shows the structure of the intake system and exhaust system of an engine. It is a schematic block diagram of the electric power supply system which concerns on an idle stop system. It is a flowchart which shows the control which concerns on an automatic restart of an engine.

Explanation of symbols

1 Engine 2 ECU (automatic stop / start control means)
35 Door open sensor (door open detection means)
37 Air conditioner switch 54 Start motor 56 Warning device (warning means)
80a main battery 80b sub-battery 82c third load group (hill holder mechanism)

Claims (4)

It is determined whether or not a predetermined automatic stop condition is satisfied, and when the automatic stop condition is satisfied, the engine is automatically stopped, and after the automatic stop of the engine, the first related to the driver's intention to start The second restart condition related to the request on the vehicle side is satisfied, including the restart condition, the battery condition that the battery voltage or the state of charge of the battery has fallen below the threshold, and the condition relating to the operation request of the air conditioner. An automatic stop start control means for restarting the engine when the first restart condition or the second restart condition is satisfied,
Door opening detecting means for detecting that the door of the vehicle has been opened; and
Warning means for giving a warning in response to the door being opened by detection of the door opening detection means during the automatic stop of the engine,
The automatic stop and start control means, during the automatic stop of the engine, when it is detected that the door is opened by the door opening detection means, among the second restart condition, the threshold of the battery condition values, along with lowering in the battery condition is met difficulty Kunar so, by canceling conditions regarding operation demand of the air conditioning system, while the battery condition is to perform a restart of the adult standing was sometimes the engine, the An automatic engine stop device that prohibits restarting of the engine even when there is an air conditioner operation request. The automatic engine stop device according to claim 1,
The automatic stop and start control means, during the automatic stop of the engine, when the door is opened is detected by said door opening detecting means, the pre-noted threshold, changing only the smaller amount set in advance Automatic engine stop device. The automatic engine stop device according to claim 1,
A main battery for supplying electric power to an electric load mounted on the vehicle during the automatic stop of the engine;
A sub-battery that restarts the engine that has been automatically stopped by supplying power to the starting motor; and
Battery state detection means for detecting the voltage or charge state of the main and sub batteries, respectively,
The automatic stop and start control means, said detected by the battery state detecting means based on the voltage or state of charge of the main battery, determines whether battery conditions included in the second restart condition is satisfied Automatic engine stop device. The automatic engine stop device according to claim 3,
An automatic engine stop device for an engine, in which an electric load to which electric power is supplied from the main battery includes a hill holder mechanism that maintains a brake fluid pressure while the vehicle is stopped.

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